tree-ssa-sccvn.h (vn_eliminate): Declare.

2017-10-25  Richard Biener  <rguenther@suse.de>

	* tree-ssa-sccvn.h (vn_eliminate): Declare.
	* tree-ssa-pre.c (class eliminate_dom_walker, eliminate,
	class pass_fre): Move to ...
	* tree-ssa-sccvn.c (class eliminate_dom_walker, vn_eliminate,
	class pass_fre): ... here and adjust for statistics.

From-SVN: r254074

1 files changed, 1 insertions, 867 deletions

diff --git a/gcc/tree-ssa-pre.c b/gcc/tree-ssa-pre.c
index ad7a0f1..e4189d1 100644
--- a/gcc/tree-ssa-pre.c
+++ b/gcc/tree-ssa-pre.c
@@ -39,7 +39,6 @@ along with GCC; see the file COPYING3.  If not see
 #include "gimplify.h"
 #include "gimple-iterator.h"
 #include "tree-cfg.h"
-#include "tree-ssa-loop.h"
 #include "tree-into-ssa.h"
 #include "tree-dfa.h"
 #include "tree-ssa.h"
@@ -50,9 +49,7 @@ along with GCC; see the file COPYING3.  If not see
 #include "dbgcnt.h"
 #include "domwalk.h"
 #include "tree-ssa-propagate.h"
-#include "ipa-utils.h"
 #include "tree-cfgcleanup.h"
-#include "langhooks.h"
 #include "alias.h"
 
 /* Even though this file is called tree-ssa-pre.c, we actually
@@ -516,9 +513,6 @@ typedef struct bb_bitmap_sets
    optimization PRE was able to perform.  */
 static struct
 {
-  /* The number of RHS computations eliminated by PRE.  */
-  int eliminations;
-
   /* The number of new expressions/temporaries generated by PRE.  */
   int insertions;
 
@@ -4036,807 +4030,6 @@ compute_avail (void)
   free (worklist);
 }
 
-class eliminate_dom_walker : public dom_walker
-{
-public:
-  eliminate_dom_walker (cdi_direction direction, bool do_pre_);
-  ~eliminate_dom_walker ();
-
-  virtual edge before_dom_children (basic_block);
-  virtual void after_dom_children (basic_block);
-
-  tree eliminate_avail (tree op);
-  void eliminate_push_avail (tree op);
-  tree eliminate_insert (gimple_stmt_iterator *gsi, tree val);
-
-  bool do_pre;
-  unsigned int el_todo;
-
-  /* Blocks with statements that have had their EH properties changed.  */
-  bitmap need_eh_cleanup;
-
-  /* Blocks with statements that have had their AB properties changed.  */
-  bitmap need_ab_cleanup;
-
-  auto_vec<gimple *> to_remove;
-  auto_vec<gimple *> to_fixup;
-  auto_vec<tree> avail;
-  auto_vec<tree> avail_stack;
-};
-
-eliminate_dom_walker::eliminate_dom_walker (cdi_direction direction,
-					    bool do_pre_)
-  : dom_walker (direction), do_pre (do_pre_), el_todo (0)
-{
-  need_eh_cleanup = BITMAP_ALLOC (NULL);
-  need_ab_cleanup = BITMAP_ALLOC (NULL);
-}
-
-eliminate_dom_walker::~eliminate_dom_walker ()
-{
-  BITMAP_FREE (need_eh_cleanup);
-  BITMAP_FREE (need_ab_cleanup);
-}
-
-/* Return a leader for OP that is available at the current point of the
-   eliminate domwalk.  */
-
-tree
-eliminate_dom_walker::eliminate_avail (tree op)
-{
-  tree valnum = VN_INFO (op)->valnum;
-  if (TREE_CODE (valnum) == SSA_NAME)
-    {
-      if (SSA_NAME_IS_DEFAULT_DEF (valnum))
-	return valnum;
-      if (avail.length () > SSA_NAME_VERSION (valnum))
-	return avail[SSA_NAME_VERSION (valnum)];
-    }
-  else if (is_gimple_min_invariant (valnum))
-    return valnum;
-  return NULL_TREE;
-}
-
-/* At the current point of the eliminate domwalk make OP available.  */
-
-void
-eliminate_dom_walker::eliminate_push_avail (tree op)
-{
-  tree valnum = VN_INFO (op)->valnum;
-  if (TREE_CODE (valnum) == SSA_NAME)
-    {
-      if (avail.length () <= SSA_NAME_VERSION (valnum))
-	avail.safe_grow_cleared (SSA_NAME_VERSION (valnum) + 1);
-      tree pushop = op;
-      if (avail[SSA_NAME_VERSION (valnum)])
-	pushop = avail[SSA_NAME_VERSION (valnum)];
-      avail_stack.safe_push (pushop);
-      avail[SSA_NAME_VERSION (valnum)] = op;
-    }
-}
-
-/* Insert the expression recorded by SCCVN for VAL at *GSI.  Returns
-   the leader for the expression if insertion was successful.  */
-
-tree
-eliminate_dom_walker::eliminate_insert (gimple_stmt_iterator *gsi, tree val)
-{
-  /* We can insert a sequence with a single assignment only.  */
-  gimple_seq stmts = VN_INFO (val)->expr;
-  if (!gimple_seq_singleton_p (stmts))
-    return NULL_TREE;
-  gassign *stmt = dyn_cast <gassign *> (gimple_seq_first_stmt (stmts));
-  if (!stmt
-      || (!CONVERT_EXPR_CODE_P (gimple_assign_rhs_code (stmt))
-	  && gimple_assign_rhs_code (stmt) != VIEW_CONVERT_EXPR
-	  && gimple_assign_rhs_code (stmt) != BIT_FIELD_REF
-	  && (gimple_assign_rhs_code (stmt) != BIT_AND_EXPR
-	      || TREE_CODE (gimple_assign_rhs2 (stmt)) != INTEGER_CST)))
-    return NULL_TREE;
-
-  tree op = gimple_assign_rhs1 (stmt);
-  if (gimple_assign_rhs_code (stmt) == VIEW_CONVERT_EXPR
-      || gimple_assign_rhs_code (stmt) == BIT_FIELD_REF)
-    op = TREE_OPERAND (op, 0);
-  tree leader = TREE_CODE (op) == SSA_NAME ? eliminate_avail (op) : op;
-  if (!leader)
-    return NULL_TREE;
-
-  tree res;
-  stmts = NULL;
-  if (gimple_assign_rhs_code (stmt) == BIT_FIELD_REF)
-    res = gimple_build (&stmts, BIT_FIELD_REF,
-			TREE_TYPE (val), leader,
-			TREE_OPERAND (gimple_assign_rhs1 (stmt), 1),
-			TREE_OPERAND (gimple_assign_rhs1 (stmt), 2));
-  else if (gimple_assign_rhs_code (stmt) == BIT_AND_EXPR)
-    res = gimple_build (&stmts, BIT_AND_EXPR,
-			TREE_TYPE (val), leader, gimple_assign_rhs2 (stmt));
-  else
-    res = gimple_build (&stmts, gimple_assign_rhs_code (stmt),
-			TREE_TYPE (val), leader);
-  if (TREE_CODE (res) != SSA_NAME
-      || SSA_NAME_IS_DEFAULT_DEF (res)
-      || gimple_bb (SSA_NAME_DEF_STMT (res)))
-    {
-      gimple_seq_discard (stmts);
-
-      /* During propagation we have to treat SSA info conservatively
-         and thus we can end up simplifying the inserted expression
-	 at elimination time to sth not defined in stmts.  */
-      /* But then this is a redundancy we failed to detect.  Which means
-         res now has two values.  That doesn't play well with how
-	 we track availability here, so give up.  */
-      if (dump_file && (dump_flags & TDF_DETAILS))
-	{
-	  if (TREE_CODE (res) == SSA_NAME)
-	    res = eliminate_avail (res);
-	  if (res)
-	    {
-	      fprintf (dump_file, "Failed to insert expression for value ");
-	      print_generic_expr (dump_file, val);
-	      fprintf (dump_file, " which is really fully redundant to ");
-	      print_generic_expr (dump_file, res);
-	      fprintf (dump_file, "\n");
-	    }
-	}
-
-      return NULL_TREE;
-    }
-  else
-    {
-      gsi_insert_seq_before (gsi, stmts, GSI_SAME_STMT);
-      VN_INFO_GET (res)->valnum = val;
-    }
-
-  pre_stats.insertions++;
-  if (dump_file && (dump_flags & TDF_DETAILS))
-    {
-      fprintf (dump_file, "Inserted ");
-      print_gimple_stmt (dump_file, SSA_NAME_DEF_STMT (res), 0);
-    }
-
-  return res;
-}
-
-
-
-/* Perform elimination for the basic-block B during the domwalk.  */
-
-edge
-eliminate_dom_walker::before_dom_children (basic_block b)
-{
-  /* Mark new bb.  */
-  avail_stack.safe_push (NULL_TREE);
-
-  /* Skip unreachable blocks marked unreachable during the SCCVN domwalk.  */
-  edge_iterator ei;
-  edge e;
-  FOR_EACH_EDGE (e, ei, b->preds)
-    if (e->flags & EDGE_EXECUTABLE)
-      break;
-  if (! e)
-    return NULL;
-
-  for (gphi_iterator gsi = gsi_start_phis (b); !gsi_end_p (gsi);)
-    {
-      gphi *phi = gsi.phi ();
-      tree res = PHI_RESULT (phi);
-
-      if (virtual_operand_p (res))
-	{
-	  gsi_next (&gsi);
-	  continue;
-	}
-
-      tree sprime = eliminate_avail (res);
-      if (sprime
-	  && sprime != res)
-	{
-	  if (dump_file && (dump_flags & TDF_DETAILS))
-	    {
-	      fprintf (dump_file, "Replaced redundant PHI node defining ");
-	      print_generic_expr (dump_file, res);
-	      fprintf (dump_file, " with ");
-	      print_generic_expr (dump_file, sprime);
-	      fprintf (dump_file, "\n");
-	    }
-
-	  /* If we inserted this PHI node ourself, it's not an elimination.  */
-	  if (inserted_exprs
-	      && bitmap_bit_p (inserted_exprs, SSA_NAME_VERSION (res)))
-	    pre_stats.phis--;
-	  else
-	    pre_stats.eliminations++;
-
-	  /* If we will propagate into all uses don't bother to do
-	     anything.  */
-	  if (may_propagate_copy (res, sprime))
-	    {
-	      /* Mark the PHI for removal.  */
-	      to_remove.safe_push (phi);
-	      gsi_next (&gsi);
-	      continue;
-	    }
-
-	  remove_phi_node (&gsi, false);
-
-	  if (!useless_type_conversion_p (TREE_TYPE (res), TREE_TYPE (sprime)))
-	    sprime = fold_convert (TREE_TYPE (res), sprime);
-	  gimple *stmt = gimple_build_assign (res, sprime);
-	  gimple_stmt_iterator gsi2 = gsi_after_labels (b);
-	  gsi_insert_before (&gsi2, stmt, GSI_NEW_STMT);
-	  continue;
-	}
-
-      eliminate_push_avail (res);
-      gsi_next (&gsi);
-    }
-
-  for (gimple_stmt_iterator gsi = gsi_start_bb (b);
-       !gsi_end_p (gsi);
-       gsi_next (&gsi))
-    {
-      tree sprime = NULL_TREE;
-      gimple *stmt = gsi_stmt (gsi);
-      tree lhs = gimple_get_lhs (stmt);
-      if (lhs && TREE_CODE (lhs) == SSA_NAME
-	  && !gimple_has_volatile_ops (stmt)
-	  /* See PR43491.  Do not replace a global register variable when
-	     it is a the RHS of an assignment.  Do replace local register
-	     variables since gcc does not guarantee a local variable will
-	     be allocated in register.
-	     ???  The fix isn't effective here.  This should instead
-	     be ensured by not value-numbering them the same but treating
-	     them like volatiles?  */
-	  && !(gimple_assign_single_p (stmt)
-	       && (TREE_CODE (gimple_assign_rhs1 (stmt)) == VAR_DECL
-		   && DECL_HARD_REGISTER (gimple_assign_rhs1 (stmt))
-		   && is_global_var (gimple_assign_rhs1 (stmt)))))
-	{
-	  sprime = eliminate_avail (lhs);
-	  if (!sprime)
-	    {
-	      /* If there is no existing usable leader but SCCVN thinks
-		 it has an expression it wants to use as replacement,
-		 insert that.  */
-	      tree val = VN_INFO (lhs)->valnum;
-	      if (val != VN_TOP
-		  && TREE_CODE (val) == SSA_NAME
-		  && VN_INFO (val)->needs_insertion
-		  && VN_INFO (val)->expr != NULL
-		  && (sprime = eliminate_insert (&gsi, val)) != NULL_TREE)
-		eliminate_push_avail (sprime);
-	    }
-
-	  /* If this now constitutes a copy duplicate points-to
-	     and range info appropriately.  This is especially
-	     important for inserted code.  See tree-ssa-copy.c
-	     for similar code.  */
-	  if (sprime
-	      && TREE_CODE (sprime) == SSA_NAME)
-	    {
-	      basic_block sprime_b = gimple_bb (SSA_NAME_DEF_STMT (sprime));
-	      if (POINTER_TYPE_P (TREE_TYPE (lhs))
-		  && VN_INFO_PTR_INFO (lhs)
-		  && ! VN_INFO_PTR_INFO (sprime))
-		{
-		  duplicate_ssa_name_ptr_info (sprime,
-					       VN_INFO_PTR_INFO (lhs));
-		  if (b != sprime_b)
-		    mark_ptr_info_alignment_unknown
-			(SSA_NAME_PTR_INFO (sprime));
-		}
-	      else if (INTEGRAL_TYPE_P (TREE_TYPE (lhs))
-		       && VN_INFO_RANGE_INFO (lhs)
-		       && ! VN_INFO_RANGE_INFO (sprime)
-		       && b == sprime_b)
-		duplicate_ssa_name_range_info (sprime,
-					       VN_INFO_RANGE_TYPE (lhs),
-					       VN_INFO_RANGE_INFO (lhs));
-	    }
-
-	  /* Inhibit the use of an inserted PHI on a loop header when
-	     the address of the memory reference is a simple induction
-	     variable.  In other cases the vectorizer won't do anything
-	     anyway (either it's loop invariant or a complicated
-	     expression).  */
-	  if (sprime
-	      && TREE_CODE (sprime) == SSA_NAME
-	      && do_pre
-	      && (flag_tree_loop_vectorize || flag_tree_parallelize_loops > 1)
-	      && loop_outer (b->loop_father)
-	      && has_zero_uses (sprime)
-	      && bitmap_bit_p (inserted_exprs, SSA_NAME_VERSION (sprime))
-	      && gimple_assign_load_p (stmt))
-	    {
-	      gimple *def_stmt = SSA_NAME_DEF_STMT (sprime);
-	      basic_block def_bb = gimple_bb (def_stmt);
-	      if (gimple_code (def_stmt) == GIMPLE_PHI
-		  && def_bb->loop_father->header == def_bb)
-		{
-		  loop_p loop = def_bb->loop_father;
-		  ssa_op_iter iter;
-		  tree op;
-		  bool found = false;
-		  FOR_EACH_SSA_TREE_OPERAND (op, stmt, iter, SSA_OP_USE)
-		    {
-		      affine_iv iv;
-		      def_bb = gimple_bb (SSA_NAME_DEF_STMT (op));
-		      if (def_bb
-			  && flow_bb_inside_loop_p (loop, def_bb)
-			  && simple_iv (loop, loop, op, &iv, true))
-			{
-			  found = true;
-			  break;
-			}
-		    }
-		  if (found)
-		    {
-		      if (dump_file && (dump_flags & TDF_DETAILS))
-			{
-			  fprintf (dump_file, "Not replacing ");
-			  print_gimple_expr (dump_file, stmt, 0);
-			  fprintf (dump_file, " with ");
-			  print_generic_expr (dump_file, sprime);
-			  fprintf (dump_file, " which would add a loop"
-				   " carried dependence to loop %d\n",
-				   loop->num);
-			}
-		      /* Don't keep sprime available.  */
-		      sprime = NULL_TREE;
-		    }
-		}
-	    }
-
-	  if (sprime)
-	    {
-	      /* If we can propagate the value computed for LHS into
-		 all uses don't bother doing anything with this stmt.  */
-	      if (may_propagate_copy (lhs, sprime))
-		{
-		  /* Mark it for removal.  */
-		  to_remove.safe_push (stmt);
-
-		  /* ???  Don't count copy/constant propagations.  */
-		  if (gimple_assign_single_p (stmt)
-		      && (TREE_CODE (gimple_assign_rhs1 (stmt)) == SSA_NAME
-			  || gimple_assign_rhs1 (stmt) == sprime))
-		    continue;
-
-		  if (dump_file && (dump_flags & TDF_DETAILS))
-		    {
-		      fprintf (dump_file, "Replaced ");
-		      print_gimple_expr (dump_file, stmt, 0);
-		      fprintf (dump_file, " with ");
-		      print_generic_expr (dump_file, sprime);
-		      fprintf (dump_file, " in all uses of ");
-		      print_gimple_stmt (dump_file, stmt, 0);
-		    }
-
-		  pre_stats.eliminations++;
-		  continue;
-		}
-
-	      /* If this is an assignment from our leader (which
-	         happens in the case the value-number is a constant)
-		 then there is nothing to do.  */
-	      if (gimple_assign_single_p (stmt)
-		  && sprime == gimple_assign_rhs1 (stmt))
-		continue;
-
-	      /* Else replace its RHS.  */
-	      bool can_make_abnormal_goto
-		  = is_gimple_call (stmt)
-		  && stmt_can_make_abnormal_goto (stmt);
-
-	      if (dump_file && (dump_flags & TDF_DETAILS))
-		{
-		  fprintf (dump_file, "Replaced ");
-		  print_gimple_expr (dump_file, stmt, 0);
-		  fprintf (dump_file, " with ");
-		  print_generic_expr (dump_file, sprime);
-		  fprintf (dump_file, " in ");
-		  print_gimple_stmt (dump_file, stmt, 0);
-		}
-
-	      pre_stats.eliminations++;
-	      gimple *orig_stmt = stmt;
-	      if (!useless_type_conversion_p (TREE_TYPE (lhs),
-					      TREE_TYPE (sprime)))
-		sprime = fold_convert (TREE_TYPE (lhs), sprime);
-	      tree vdef = gimple_vdef (stmt);
-	      tree vuse = gimple_vuse (stmt);
-	      propagate_tree_value_into_stmt (&gsi, sprime);
-	      stmt = gsi_stmt (gsi);
-	      update_stmt (stmt);
-	      if (vdef != gimple_vdef (stmt))
-		VN_INFO (vdef)->valnum = vuse;
-
-	      /* If we removed EH side-effects from the statement, clean
-		 its EH information.  */
-	      if (maybe_clean_or_replace_eh_stmt (orig_stmt, stmt))
-		{
-		  bitmap_set_bit (need_eh_cleanup,
-				  gimple_bb (stmt)->index);
-		  if (dump_file && (dump_flags & TDF_DETAILS))
-		    fprintf (dump_file, "  Removed EH side-effects.\n");
-		}
-
-	      /* Likewise for AB side-effects.  */
-	      if (can_make_abnormal_goto
-		  && !stmt_can_make_abnormal_goto (stmt))
-		{
-		  bitmap_set_bit (need_ab_cleanup,
-				  gimple_bb (stmt)->index);
-		  if (dump_file && (dump_flags & TDF_DETAILS))
-		    fprintf (dump_file, "  Removed AB side-effects.\n");
-		}
-
-	      continue;
-	    }
-	}
-
-      /* If the statement is a scalar store, see if the expression
-         has the same value number as its rhs.  If so, the store is
-         dead.  */
-      if (gimple_assign_single_p (stmt)
-	  && !gimple_has_volatile_ops (stmt)
-	  && !is_gimple_reg (gimple_assign_lhs (stmt))
-	  && (TREE_CODE (gimple_assign_rhs1 (stmt)) == SSA_NAME
-	      || is_gimple_min_invariant (gimple_assign_rhs1 (stmt))))
-	{
-	  tree val;
-	  tree rhs = gimple_assign_rhs1 (stmt);
-	  vn_reference_t vnresult;
-	  val = vn_reference_lookup (lhs, gimple_vuse (stmt), VN_WALKREWRITE,
-				     &vnresult, false);
-	  if (TREE_CODE (rhs) == SSA_NAME)
-	    rhs = VN_INFO (rhs)->valnum;
-	  if (val
-	      && operand_equal_p (val, rhs, 0))
-	    {
-	      /* We can only remove the later store if the former aliases
-		 at least all accesses the later one does or if the store
-		 was to readonly memory storing the same value.  */
-	      alias_set_type set = get_alias_set (lhs);
-	      if (! vnresult
-		  || vnresult->set == set
-		  || alias_set_subset_of (set, vnresult->set))
-		{
-		  if (dump_file && (dump_flags & TDF_DETAILS))
-		    {
-		      fprintf (dump_file, "Deleted redundant store ");
-		      print_gimple_stmt (dump_file, stmt, 0);
-		    }
-
-		  /* Queue stmt for removal.  */
-		  to_remove.safe_push (stmt);
-		  continue;
-		}
-	    }
-	}
-
-      /* If this is a control statement value numbering left edges
-	 unexecuted on force the condition in a way consistent with
-	 that.  */
-      if (gcond *cond = dyn_cast <gcond *> (stmt))
-	{
-	  if ((EDGE_SUCC (b, 0)->flags & EDGE_EXECUTABLE)
-	      ^ (EDGE_SUCC (b, 1)->flags & EDGE_EXECUTABLE))
-	    {
-              if (dump_file && (dump_flags & TDF_DETAILS))
-                {
-                  fprintf (dump_file, "Removing unexecutable edge from ");
-		  print_gimple_stmt (dump_file, stmt, 0);
-                }
-	      if (((EDGE_SUCC (b, 0)->flags & EDGE_TRUE_VALUE) != 0)
-		  == ((EDGE_SUCC (b, 0)->flags & EDGE_EXECUTABLE) != 0))
-		gimple_cond_make_true (cond);
-	      else
-		gimple_cond_make_false (cond);
-	      update_stmt (cond);
-	      el_todo |= TODO_cleanup_cfg;
-	      continue;
-	    }
-	}
-
-      bool can_make_abnormal_goto = stmt_can_make_abnormal_goto (stmt);
-      bool was_noreturn = (is_gimple_call (stmt)
-			   && gimple_call_noreturn_p (stmt));
-      tree vdef = gimple_vdef (stmt);
-      tree vuse = gimple_vuse (stmt);
-
-      /* If we didn't replace the whole stmt (or propagate the result
-         into all uses), replace all uses on this stmt with their
-	 leaders.  */
-      bool modified = false;
-      use_operand_p use_p;
-      ssa_op_iter iter;
-      FOR_EACH_SSA_USE_OPERAND (use_p, stmt, iter, SSA_OP_USE)
-	{
-	  tree use = USE_FROM_PTR (use_p);
-	  /* ???  The call code above leaves stmt operands un-updated.  */
-	  if (TREE_CODE (use) != SSA_NAME)
-	    continue;
-	  tree sprime = eliminate_avail (use);
-	  if (sprime && sprime != use
-	      && may_propagate_copy (use, sprime)
-	      /* We substitute into debug stmts to avoid excessive
-	         debug temporaries created by removed stmts, but we need
-		 to avoid doing so for inserted sprimes as we never want
-		 to create debug temporaries for them.  */
-	      && (!inserted_exprs
-		  || TREE_CODE (sprime) != SSA_NAME
-		  || !is_gimple_debug (stmt)
-		  || !bitmap_bit_p (inserted_exprs, SSA_NAME_VERSION (sprime))))
-	    {
-	      propagate_value (use_p, sprime);
-	      modified = true;
-	    }
-	}
-
-      /* Fold the stmt if modified, this canonicalizes MEM_REFs we propagated
-         into which is a requirement for the IPA devirt machinery.  */
-      gimple *old_stmt = stmt;
-      if (modified)
-	{
-	  /* If a formerly non-invariant ADDR_EXPR is turned into an
-	     invariant one it was on a separate stmt.  */
-	  if (gimple_assign_single_p (stmt)
-	      && TREE_CODE (gimple_assign_rhs1 (stmt)) == ADDR_EXPR)
-	    recompute_tree_invariant_for_addr_expr (gimple_assign_rhs1 (stmt));
-	  gimple_stmt_iterator prev = gsi;
-	  gsi_prev (&prev);
-	  if (fold_stmt (&gsi))
-	    {
-	      /* fold_stmt may have created new stmts inbetween
-		 the previous stmt and the folded stmt.  Mark
-		 all defs created there as varying to not confuse
-		 the SCCVN machinery as we're using that even during
-		 elimination.  */
-	      if (gsi_end_p (prev))
-		prev = gsi_start_bb (b);
-	      else
-		gsi_next (&prev);
-	      if (gsi_stmt (prev) != gsi_stmt (gsi))
-		do
-		  {
-		    tree def;
-		    ssa_op_iter dit;
-		    FOR_EACH_SSA_TREE_OPERAND (def, gsi_stmt (prev),
-					       dit, SSA_OP_ALL_DEFS)
-		      /* As existing DEFs may move between stmts
-			 we have to guard VN_INFO_GET.  */
-		      if (! has_VN_INFO (def))
-			VN_INFO_GET (def)->valnum = def;
-		    if (gsi_stmt (prev) == gsi_stmt (gsi))
-		      break;
-		    gsi_next (&prev);
-		  }
-		while (1);
-	    }
-	  stmt = gsi_stmt (gsi);
-	  /* In case we folded the stmt away schedule the NOP for removal.  */
-	  if (gimple_nop_p (stmt))
-	    to_remove.safe_push (stmt);
-	}
-
-      /* Visit indirect calls and turn them into direct calls if
-	 possible using the devirtualization machinery.  Do this before
-	 checking for required EH/abnormal/noreturn cleanup as devird
-	 may expose more of those.  */
-      if (gcall *call_stmt = dyn_cast <gcall *> (stmt))
-	{
-	  tree fn = gimple_call_fn (call_stmt);
-	  if (fn
-	      && flag_devirtualize
-	      && virtual_method_call_p (fn))
-	    {
-	      tree otr_type = obj_type_ref_class (fn);
-	      unsigned HOST_WIDE_INT otr_tok
-		= tree_to_uhwi (OBJ_TYPE_REF_TOKEN (fn));
-	      tree instance;
-	      ipa_polymorphic_call_context context (current_function_decl,
-						    fn, stmt, &instance);
-	      context.get_dynamic_type (instance, OBJ_TYPE_REF_OBJECT (fn),
-					otr_type, stmt);
-	      bool final;
-	      vec <cgraph_node *> targets
-		= possible_polymorphic_call_targets (obj_type_ref_class (fn),
-						     otr_tok, context, &final);
-	      if (dump_file)
-		dump_possible_polymorphic_call_targets (dump_file, 
-							obj_type_ref_class (fn),
-							otr_tok, context);
-	      if (final && targets.length () <= 1 && dbg_cnt (devirt))
-		{
-		  tree fn;
-		  if (targets.length () == 1)
-		    fn = targets[0]->decl;
-		  else
-		    fn = builtin_decl_implicit (BUILT_IN_UNREACHABLE);
-		  if (dump_enabled_p ())
-		    {
-		      location_t loc = gimple_location (stmt);
-		      dump_printf_loc (MSG_OPTIMIZED_LOCATIONS, loc,
-				       "converting indirect call to "
-				       "function %s\n",
-				       lang_hooks.decl_printable_name (fn, 2));
-		    }
-		  gimple_call_set_fndecl (call_stmt, fn);
-		  /* If changing the call to __builtin_unreachable
-		     or similar noreturn function, adjust gimple_call_fntype
-		     too.  */
-		  if (gimple_call_noreturn_p (call_stmt)
-		      && VOID_TYPE_P (TREE_TYPE (TREE_TYPE (fn)))
-		      && TYPE_ARG_TYPES (TREE_TYPE (fn))
-		      && (TREE_VALUE (TYPE_ARG_TYPES (TREE_TYPE (fn)))
-			  == void_type_node))
-		    gimple_call_set_fntype (call_stmt, TREE_TYPE (fn));
-		  maybe_remove_unused_call_args (cfun, call_stmt);
-		  modified = true;
-		}
-	    }
-	}
-
-      if (modified)
-	{
-	  /* When changing a call into a noreturn call, cfg cleanup
-	     is needed to fix up the noreturn call.  */
-	  if (!was_noreturn
-	      && is_gimple_call (stmt) && gimple_call_noreturn_p (stmt))
-	    to_fixup.safe_push  (stmt);
-	  /* When changing a condition or switch into one we know what
-	     edge will be executed, schedule a cfg cleanup.  */
-	  if ((gimple_code (stmt) == GIMPLE_COND
-	       && (gimple_cond_true_p (as_a <gcond *> (stmt))
-		   || gimple_cond_false_p (as_a <gcond *> (stmt))))
-	      || (gimple_code (stmt) == GIMPLE_SWITCH
-		  && TREE_CODE (gimple_switch_index
-				  (as_a <gswitch *> (stmt))) == INTEGER_CST))
-	    el_todo |= TODO_cleanup_cfg;
-	  /* If we removed EH side-effects from the statement, clean
-	     its EH information.  */
-	  if (maybe_clean_or_replace_eh_stmt (old_stmt, stmt))
-	    {
-	      bitmap_set_bit (need_eh_cleanup,
-			      gimple_bb (stmt)->index);
-	      if (dump_file && (dump_flags & TDF_DETAILS))
-		fprintf (dump_file, "  Removed EH side-effects.\n");
-	    }
-	  /* Likewise for AB side-effects.  */
-	  if (can_make_abnormal_goto
-	      && !stmt_can_make_abnormal_goto (stmt))
-	    {
-	      bitmap_set_bit (need_ab_cleanup,
-			      gimple_bb (stmt)->index);
-	      if (dump_file && (dump_flags & TDF_DETAILS))
-		fprintf (dump_file, "  Removed AB side-effects.\n");
-	    }
-	  update_stmt (stmt);
-	  if (vdef != gimple_vdef (stmt))
-	    VN_INFO (vdef)->valnum = vuse;
-	}
-
-      /* Make new values available - for fully redundant LHS we
-         continue with the next stmt above and skip this.  */
-      def_operand_p defp;
-      FOR_EACH_SSA_DEF_OPERAND (defp, stmt, iter, SSA_OP_DEF)
-	eliminate_push_avail (DEF_FROM_PTR (defp));
-    }
-
-  /* Replace destination PHI arguments.  */
-  FOR_EACH_EDGE (e, ei, b->succs)
-    if (e->flags & EDGE_EXECUTABLE)
-      for (gphi_iterator gsi = gsi_start_phis (e->dest);
-	   !gsi_end_p (gsi);
-	   gsi_next (&gsi))
-	{
-	  gphi *phi = gsi.phi ();
-	  use_operand_p use_p = PHI_ARG_DEF_PTR_FROM_EDGE (phi, e);
-	  tree arg = USE_FROM_PTR (use_p);
-	  if (TREE_CODE (arg) != SSA_NAME
-	      || virtual_operand_p (arg))
-	    continue;
-	  tree sprime = eliminate_avail (arg);
-	  if (sprime && may_propagate_copy (arg, sprime))
-	    propagate_value (use_p, sprime);
-	}
-  return NULL;
-}
-
-/* Make no longer available leaders no longer available.  */
-
-void
-eliminate_dom_walker::after_dom_children (basic_block)
-{
-  tree entry;
-  while ((entry = avail_stack.pop ()) != NULL_TREE)
-    {
-      tree valnum = VN_INFO (entry)->valnum;
-      tree old = avail[SSA_NAME_VERSION (valnum)];
-      if (old == entry)
-	avail[SSA_NAME_VERSION (valnum)] = NULL_TREE;
-      else
-	avail[SSA_NAME_VERSION (valnum)] = entry;
-    }
-}
-
-/* Eliminate fully redundant computations.  */
-
-static unsigned int
-eliminate (bool do_pre)
-{
-  eliminate_dom_walker el (CDI_DOMINATORS, do_pre);
-  el.avail.reserve (num_ssa_names);
-
-  el.walk (cfun->cfg->x_entry_block_ptr);
-
-  /* We cannot remove stmts during BB walk, especially not release SSA
-     names there as this confuses the VN machinery.  The stmts ending
-     up in to_remove are either stores or simple copies.
-     Remove stmts in reverse order to make debug stmt creation possible.  */
-  while (!el.to_remove.is_empty ())
-    {
-      gimple *stmt = el.to_remove.pop ();
-
-      if (dump_file && (dump_flags & TDF_DETAILS))
-	{
-	  fprintf (dump_file, "Removing dead stmt ");
-	  print_gimple_stmt (dump_file, stmt, 0, 0);
-	}
-
-      gimple_stmt_iterator gsi = gsi_for_stmt (stmt);
-      if (gimple_code (stmt) == GIMPLE_PHI)
-	remove_phi_node (&gsi, true);
-      else
-	{
-	  basic_block bb = gimple_bb (stmt);
-	  unlink_stmt_vdef (stmt);
-	  if (gsi_remove (&gsi, true))
-	    bitmap_set_bit (el.need_eh_cleanup, bb->index);
-	  if (is_gimple_call (stmt) && stmt_can_make_abnormal_goto (stmt))
-	    bitmap_set_bit (el.need_ab_cleanup, bb->index);
-	  release_defs (stmt);
-	}
-
-      /* Removing a stmt may expose a forwarder block.  */
-      el.el_todo |= TODO_cleanup_cfg;
-    }
-
-  /* Fixup stmts that became noreturn calls.  This may require splitting
-     blocks and thus isn't possible during the dominator walk.  Do this
-     in reverse order so we don't inadvertedly remove a stmt we want to
-     fixup by visiting a dominating now noreturn call first.  */
-  while (!el.to_fixup.is_empty ())
-    {
-      gimple *stmt = el.to_fixup.pop ();
-
-      if (dump_file && (dump_flags & TDF_DETAILS))
-	{
-	  fprintf (dump_file, "Fixing up noreturn call ");
-	  print_gimple_stmt (dump_file, stmt, 0);
-	}
-
-      if (fixup_noreturn_call (stmt))
-	el.el_todo |= TODO_cleanup_cfg;
-    }
-
-  bool do_eh_cleanup = !bitmap_empty_p (el.need_eh_cleanup);
-  bool do_ab_cleanup = !bitmap_empty_p (el.need_ab_cleanup);
-
-  if (do_eh_cleanup)
-    gimple_purge_all_dead_eh_edges (el.need_eh_cleanup);
-
-  if (do_ab_cleanup)
-    gimple_purge_all_dead_abnormal_call_edges (el.need_ab_cleanup);
-
-  if (do_eh_cleanup || do_ab_cleanup)
-    el.el_todo |= TODO_cleanup_cfg;
-  return el.el_todo;
-}
-
 /* Cheap DCE of a known set of possibly dead stmts.
 
    Because we don't follow exactly the standard PRE algorithm, and decide not
@@ -5023,13 +4216,12 @@ pass_pre::execute (function *fun)
   gcc_assert (!need_ssa_update_p (fun));
 
   /* Remove all the redundant expressions.  */
-  todo |= eliminate (true);
+  todo |= vn_eliminate (inserted_exprs);
 
   statistics_counter_event (fun, "Insertions", pre_stats.insertions);
   statistics_counter_event (fun, "PA inserted", pre_stats.pa_insert);
   statistics_counter_event (fun, "HOIST inserted", pre_stats.hoist_insert);
   statistics_counter_event (fun, "New PHIs", pre_stats.phis);
-  statistics_counter_event (fun, "Eliminated", pre_stats.eliminations);
 
   clear_expression_ids ();
 
@@ -5069,61 +4261,3 @@ make_pass_pre (gcc::context *ctxt)
 {
   return new pass_pre (ctxt);
 }
-
-namespace {
-
-const pass_data pass_data_fre =
-{
-  GIMPLE_PASS, /* type */
-  "fre", /* name */
-  OPTGROUP_NONE, /* optinfo_flags */
-  TV_TREE_FRE, /* tv_id */
-  ( PROP_cfg | PROP_ssa ), /* properties_required */
-  0, /* properties_provided */
-  0, /* properties_destroyed */
-  0, /* todo_flags_start */
-  0, /* todo_flags_finish */
-};
-
-class pass_fre : public gimple_opt_pass
-{
-public:
-  pass_fre (gcc::context *ctxt)
-    : gimple_opt_pass (pass_data_fre, ctxt)
-  {}
-
-  /* opt_pass methods: */
-  opt_pass * clone () { return new pass_fre (m_ctxt); }
-  virtual bool gate (function *) { return flag_tree_fre != 0; }
-  virtual unsigned int execute (function *);
-
-}; // class pass_fre
-
-unsigned int
-pass_fre::execute (function *fun)
-{
-  unsigned int todo = 0;
-
-  run_scc_vn (VN_WALKREWRITE);
-
-  memset (&pre_stats, 0, sizeof (pre_stats));
-
-  /* Remove all the redundant expressions.  */
-  todo |= eliminate (false);
-
-  scc_vn_restore_ssa_info ();
-  free_scc_vn ();
-
-  statistics_counter_event (fun, "Insertions", pre_stats.insertions);
-  statistics_counter_event (fun, "Eliminated", pre_stats.eliminations);
-
-  return todo;
-}
-
-} // anon namespace
-
-gimple_opt_pass *
-make_pass_fre (gcc::context *ctxt)
-{
-  return new pass_fre (ctxt);
-}